Electrolytic capacitors bad news for anything on full power for long-ish time

[Siwastaja]

Don't overanalyse cheap hobbyist modules. There may not be any particular strong reason for such component placement at all, or it can be anything. It's typical that similar products look similar, i.e., there is a lot of copying around.

For example, one design could have had too little DC link capacitance or damping to begin with, then after prototyping they added some extra without respinning the PCB, in this obvious way. Then others just copied this habit.

Or, the design might be all SMT, but they have access to low-cost THT elcaps; since the module thickness is limited, the capacitor must be mounted sideways, so this is the obvious way to do it. Especially, if they already need to solder wires directly to the PCB, paralleling the cap with the wires is an obvious construction technique, instead of a separate "just solder the capacitor" step.

Obviously, all this have absolutely nothing to do with the lifetime of said capacitors. For such low-hours application, designing the capacitor lifetime not to be the limiting factor is utterly trivial, just don't exceed the ripple current ratings.

It's well possible the elcap is just for damping a fairly large amount of low-ESR (ceramic) capacitance and carries only tiny part of the ripple current, not heating up at all. This is how I tend to use elcaps in power electronics, and the lifetime is practically infinite.

Proper designs derate the operating temperature spec, ripple current spec, and finally, are not overly sensitive to ESR rise. Typical mid-grade 5000 hours rating can be easily extended to 50000 hours or so. Indeed, if you take a look at randomly selected consumer electronic products from, say, 10 years ago, you will see that most have lasted for a very long time no problem whatsoever, but a few, mostly well-known, suspects fail. The reason for failure is almost always either a very cheap no-name brand, clearly exceeding the specifications, or failure to apply any derating in a product designed for large number of operating hours.

[Kjelt]

I never ever seen any SMPS from A brands such as Puls, TDK-Lambda, Traco or even a bit lesser brands as Meanwell where the caps are mounted outside the housing 
However when the output power crosses a certain threshold I do see said power supplies being fitted with a fan for active cooling.
Now the question, what has the expected less hours lifetime, a fan or an A brand 105 capacitor ?

[dmills]

The fans have a lifetime Vs temperature curve in the datasheets, just like the caps, at least if you buy proper ones and not PC modder shit.

I do NOT get the hate on for electrolytic caps, figure out the operating conditions (Design life, temperature, ripple being the big ones), read datasheets, do sums, kick purchasing in the head until they buy what you told them to, it ain't hard.

Sure you can get early failure by screwing the pooch with the sums, or by purchasing shit in the first place, and this is different to any other component how exactly? 

They are the common fail in consumer products simply because they have a relatively steep price Vs quality curve and actually have fairly well defined reliability even with the cheap stuff, so as a designer if you are told "2 Years at 8 hours a day, 45 degrees C, 1.8A ripple, 400V", you do not need to massively over design to avoid premature failures.

[tkamiya]

I did the same search OP did, but saw only small number of them has external capacitors.  I can think of a few reasons.

1)  They are labeled as input capacitor.  There is no telling what will be connected.  Used in conjunction with very small SMD components, average user won't be able to replace the cap should it blow.

2)  Some of them are so small, cap is almost half the size of the board.  (meaning including cap, board will be 50% larger)  It might be cost saving on PCB production.

3)  I bet those SMDs are auto populated by pick machine and reflowed on oven.  Can't do that with a giant big cap right near by.

4)  Many appears to use parallel/serial/whatever dozen or so SMD size caps.  So it can be done.

5)  Marketing wise, they can claim "sub-miniature and ultra-light" by excluding the cap from measurement.

[coppice]

I do NOT get the hate on for electrolytic caps, figure out the operating conditions (Design life, temperature, ripple being the big ones), read datasheets, do sums, kick purchasing in the head until they buy what you told them to, it ain't hard.

People are just dumb enough to hate the wrong thing. The electrolytics which decay into a festering mess are bad electrolytics, and deserve negative feelings. However, most electrolytics just dry out, which is the fault of the equipment designer, not the capacitor. A huge amount of electronic failures are due to poor thermal management, and electrolytics are probably the most abused parts.

[Siwastaja]

A huge amount of electronic failures are due to poor thermal management, and electrolytics are probably the most abused parts.

Likely they are, but they still get disproportionate attention; possibly because people still remember, or have heard about the "capacitor plague". Yet in reality, there are other types of typical aging failures as well.

I'm not a huge repairer myself, but having repaired a few things nevertheless (it's a good way to learn from the mistakes of others), I have seen an equivalent number of heat-damaged connectors and wire insulation! After all, PVC (and many other plastics) really suffers in long-time operation over about 60-70 degC, while an elcap is still quite OK at that temperature (if ripple current rating isn't exceeded, that is). So I have seen crispy, broken connectors and wires right next to elcaps that are still just fine.

Yet this is something absolutely no one ever talks about. Say, if the ratio of elcap : connector damage is like 3:1, the ratio of discussion thereof is some 100 000 : 1.

Many designers (or their bosses, to be fair...) still miss the fact that increasing efficiency tends to be #1 way to solve many problems. Thermal design isn't free!

[ocset]

The western middle men are forcing cost-downs on the Chinese designers which means that inevitably, during a product lifetime, the electrolytics will be down graded to poor, cheap ones that will fail in an unreasonably short space of time……the cheapest will be used that can be gotten away with.
Best is to have a checking agency in each country which checks electro’s, connectors, transient protection etc etc
The game of the middle man, is  “pay the Chinese designers as little as possible, and charge the western customers as much as possible”. (and hope EEVBloggers don’t do a teardown on you!)
Good point on connectors BTW. However, once a connector is specified and on the PCB…its not so easy to  swap it out for an el-cheapo production run…but nonetheless, great point, I have a DAB radio on which I had to take the dodgy connector off and solder the 5V straight to the PCB.

[Gyro]

The western middle men are forcing cost-downs on the Chinese designers which means that inevitably, during a product lifetime, the electrolytics will be down graded to poor, cheap ones that will fail in an unreasonably short space of time……the cheapest will be used that can be gotten away with.
Best is to have a checking agency in each country which checks electro’s, connectors, transient protection etc etc
The game of the middle man, is  “pay the Chinese designers as little as possible, and charge the western customers as much as possible”. (and hope EEVBloggers don’t do a teardown on you!)
Good point on connectors BTW. However, once a connector is specified and on the PCB…its not so easy to  swap it out for an el-cheapo production run…but nonetheless, great point, I have a DAB radio on which I had to take the dodgy connector off and solder the 5V straight to the PCB.

I don't know how you managed to transition your topic to cheap DAB radios.

Design it correctly and control your manufacturing and sourcing process correctly. If you can't do that effectively, then you are the point of failure.

Stop linking proper development and production process with random, cheap, off the shelf stuff.

[Siwastaja]

Yes, while crappy processes are in place, there is a lot of proper design & manufacturing as well.

What's best, no one is preventing you to make the change!

If your boss prevents doing proper design, get a new boss. Simple as that.

But you categorically dismissing the elcaps does not make you a very capable engineer. There are countless of cases where elcaps are either an absolute must or by far the best solution for the job.

If you design for >30 year product lifetime or high temperature (say > 70-80 degC ambient), then elcaps are likely out, but so are many many other solutions! This is not obvious at the time of design: from a 80's device, you are now more likely to find a catastrophically failed film capacitor, than a failed electrolytic capacitor! How can you be 100% sure that a modern film cap does not fail like those RIFA caps did?

[Kjelt]

The problem starts when big money corporations start selling stuff they don't understand for less money than the A brands and people start wondering why the A brands are so expensive and dtop buying them.
Then the A brand is forced to lower quality in order to keep on selling their products, hence have to replace their A brand Nichicon, Rubycon, Matsushita elco's with Maxxon, SunSing, Tadingtading brands.

This happened and is happening, examples Osram and Philips Lighting vs newcomer Ikea.
It is bad for some businesses and also for people that rather have good quality stuff than mediocre stuff that will fail in a few years, but nothing you can do against it.

People spent tons of money on certain luxury brands like Louis Vuiton and DG while those products are also made in paycheck slave countries like India and Bangladesh but refuse to pay more for quality normal usage technology products. Only the high tech products are still safe.

[coppice]

Good point on connectors BTW. However, once a connector is specified and on the PCB…its not so easy to  swap it out for an el-cheapo production run…but nonetheless, great point

Connectors are one of the easiest things to swap out during a production run. For any high quality connector that achieves even moderate success there will be third party clones of variable quality. Even the original source may produce multiple versions to suitable various pockets, using poor lifetime or poor temperature range plastics, cheaper platings and so on.

[vk6zgo]

The western middle men are forcing cost-downs on the Chinese designers which means that inevitably, during a product lifetime, the electrolytics will be down graded to poor, cheap ones that will fail in an unreasonably short space of time……the cheapest will be used that can be gotten away with.
Best is to have a checking agency in each country which checks electro’s, connectors, transient protection etc etc
The game of the middle man, is  “pay the Chinese designers as little as possible, and charge the western customers as much as possible”. (and hope EEVBloggers don’t do a teardown on you!)
Good point on connectors BTW. However, once a connector is specified and on the PCB…its not so easy to  swap it out for an el-cheapo production run…but nonetheless, great point, I have a DAB radio on which I had to take the dodgy connector off and solder the 5V straight to the PCB.

Lord Jesus. Now Treez is finally on topic.

In China, just as in Australia, & other countries, there are companies which spoil a basically  good idea, by misguided attempts to "economise", which really reduce costs by only a minimal amount, whilst degrading quality.

I worked at an Australian one like that, & also spent a lot of time working on equipment made by a Chinese representative of this category.

The Aussie one refused to accept suggestions, which although possibly costing a small amount more upfront, meant big savings in man-hours, plus greatly improved reliability.

In the case of the Chinese company, it seemed they "cheaped out" by employing inexperienced EEs for a very short time, then dispensing with their services.
Unfortunately, these "rent an EE"s were designing 2kW UHF transmitters, mainly by picking through what they could glean from the Internet.

There seemed to be nobody with any real depth of knowledge at this company, either at the Engineering or Technical level, as these transmitters did not work when we received them, & even after we sent them back, two out of five were "no go" when they returned.

After trying to get sense out of the company for months, we had to make the things work ourselves, but we still kept finding nice little  surprises.
Dry joints were common, the RF amplifiers were not tuned to the frequency we used, & the power controller circuitry would sometimes burst into oscillation.

With both companies, their crappiness could not be blamed upon the "big, bad, customer!"

[Connecteur]

Chinese manufacturers are forever being made the scapegoats for shoddy quality, but they are simply working under massive constraints often imposed on them by greedy and merciless companies in China and anywhere else in the world.  For example if you ask for a capacitor for 1/10 the going price, you may get what you ask for. For Chinese manufacturers, the consequences of failure can sometimes be dire, and the labor force sometimes work in slavery or near-slavery conditions.  The quality is understandably below standards in many cases. Other times, it's not.

But specify a capacitor with a 100 year lifespan, and a Chinese manufacturer may actually achieve it, and at a competitive price.  Quality and cost are not always inversely proportional.  Sometimes good engineering can serve both masters; longevity and cost. The myth of having to pay for better quality in every case is being disproved every day.  Countless examples exist, in Asia and elsewhere.

[tkamiya]

When customer asks for 1/10 of a price, the answer ought to be, "can't do it for that".  But it seems some places goes to reject bin and grab and handful, then sell it for that price.

Customer should also know what the fair price of a product is.  When something is offered for 1/10 of a price, they must wonder why.  Rather than just go ahead and sticking it in for their product and selling it.

Ultimate customer (that's us) should also wary of products that are disproportionately inexpensive compared to similar products.  But that's what often offered on "SALE!" and they actually SELL! 

Slave like labor condition in this day and age, that's just inexcusable - but still happens even in modern countries.  We kind of demand it by mercilessly price shopping.

Blame goes around for everybody involved.

[coppice]

When customer asks for 1/10 of a price, the answer ought to be, "can't do it for that".

Do you like going hungry?

Most engineering starts with an acceptable price. Only the most innovative things and defence projects start from any other point. Engineering is about producing something acceptable to the customer that fits the price constraint. Very often quality can suffer massively and the customer keeps on buying. They might whine and moan about problems with the product, but people always whine and moan about products. What they continue to buy in a competitive landscape is the only real measure of how they feel about what is offered to them. Setting your own standards for quality, rather than listening to the market, can leave you very hungry.

[SilverSolder]

The problem starts when big money corporations start selling stuff they don't understand for less money than the A brands and people start wondering why the A brands are so expensive and dtop buying them.
Then the A brand is forced to lower quality in order to keep on selling their products, hence have to replace their A brand Nichicon, Rubycon, Matsushita elco's with Maxxon, SunSing, Tadingtading brands.

This happened and is happening, examples Osram and Philips Lighting vs newcomer Ikea.
It is bad for some businesses and also for people that rather have good quality stuff than mediocre stuff that will fail in a few years, but nothing you can do against it.

People spent tons of money on certain luxury brands like Louis Vuiton and DG while those products are also made in paycheck slave countries like India and Bangladesh but refuse to pay more for quality normal usage technology products. Only the high tech products are still safe.

In the long run, people stop buying brands that have unreasonably short lifespans - and the brand gets a bad reputation.   IKEA knows what they are doing (long term players) and have minimum requirements that even their cheapest stuff has to meet, they make their money from huge volumes - in other words, I'd be inclined to trust cheap stuff from Ikea more than brand-X cheap stuff from a company with no history and - possibly - no future!

[tkamiya]

When customer asks for 1/10 of a price, the answer ought to be, "can't do it for that".

Do you like going hungry?

Most engineering starts with an acceptable price. Only the most innovative things and defence projects start from any other point. Engineering is about producing something acceptable to the customer that fits the price constraint. Very often quality can suffer massively and the customer keeps on buying. They might whine and moan about problems with the product, but people always whine and moan about products. What they continue to buy in a competitive landscape is the only real measure of how they feel about what is offered to them. Setting your own standards for quality, rather than listening to the market, can leave you very hungry.

If it meant having have to procure parts at TENth of price and make things that are dangerous to users, yes, I'd prefer going hungry.  I don't want that on my conscience.  Shop owner wouldn't want 80% of what he sells come back either.  That will give them cost over-run in customer care, and certainly a bad reputation.

You are talking about fairly reasonable business negotiations and demand.  I'm talking about extremes. 

[Connecteur]

Personal anecdote:  A Polish friend of mine was familiar with a light bulb factory that had operated under the communist system, and was in the process of being privatized.  These incandescent bulbs had a very long lifespan of 5-10 years, and sold for just a few pennies.  they were exported very successfully around the world for a year or two.  Soon, the factory was purchased by a western multinational light bulb manufacturer, and one of the first changes was to alter the manufacturing process to greatly shorten the lifespan.  The price was also greatly increased, and the Polish light bulb factory went out of business shortly after.

[Kjelt]

The problem starts when big money corporations start selling stuff they don't understand for less money than the A brands and people start wondering why the A brands are so expensive and dtop buying them.
Then the A brand is forced to lower quality in order to keep on selling their products, hence have to replace their A brand Nichicon, Rubycon, Matsushita elco's with Maxxon, SunSing, Tadingtading brands.

This happened and is happening, examples Osram and Philips Lighting vs newcomer Ikea.
It is bad for some businesses and also for people that rather have good quality stuff than mediocre stuff that will fail in a few years, but nothing you can do against it.

People spent tons of money on certain luxury brands like Louis Vuiton and DG while those products are also made in paycheck slave countries like India and Bangladesh but refuse to pay more for quality normal usage technology products. Only the high tech products are still safe.

In the long run, people stop buying brands that have unreasonably short lifespans - and the brand gets a bad reputation.   IKEA knows what they are doing (long term players) and have minimum requirements that even their cheapest stuff has to meet, they make their money from huge volumes - in other words, I'd be inclined to trust cheap stuff from Ikea more than brand-X cheap stuff from a company with no history and - possibly - no future!

Reread my post I never use brand X with no history. It are the A brands, players in the lighting market for hundred of years that now have no choice than to sacrifice quality and lifetime for low end consumer products to compete with newcomers that sell garbage. Ikea is pretty decent compared to some small chinese factories.
I just find that sad as many here, see the cheapo life threatening fake Apple chargers for instance.

[SilverSolder]

The problem starts when big money corporations start selling stuff they don't understand for less money than the A brands and people start wondering why the A brands are so expensive and dtop buying them.
Then the A brand is forced to lower quality in order to keep on selling their products, hence have to replace their A brand Nichicon, Rubycon, Matsushita elco's with Maxxon, SunSing, Tadingtading brands.

This happened and is happening, examples Osram and Philips Lighting vs newcomer Ikea.
It is bad for some businesses and also for people that rather have good quality stuff than mediocre stuff that will fail in a few years, but nothing you can do against it.

People spent tons of money on certain luxury brands like Louis Vuiton and DG while those products are also made in paycheck slave countries like India and Bangladesh but refuse to pay more for quality normal usage technology products. Only the high tech products are still safe.

In the long run, people stop buying brands that have unreasonably short lifespans - and the brand gets a bad reputation.   IKEA knows what they are doing (long term players) and have minimum requirements that even their cheapest stuff has to meet, they make their money from huge volumes - in other words, I'd be inclined to trust cheap stuff from Ikea more than brand-X cheap stuff from a company with no history and - possibly - no future!

Reread my post I never use brand X with no history. It are the A brands, players in the lighting market for hundred of years that now have no choice than to sacrifice quality and lifetime for low end consumer products to compete with newcomers that sell garbage. Ikea is pretty decent compared to some small chinese factories.
I just find that sad as many here, see the cheapo life threatening fake Apple chargers for instance.

There will always be a big market for garbage - and there will always be a smaller one for nicer products.  That's how the world works...  (I didn't design it, I just live here!)

[coppice]

There will always be a big market for garbage - and there will always be a smaller one for nicer products.  That's how the world works...  (I didn't design it, I just live here!)

This is basically true. The problem is the middle ground of decent quality at affordable prices can get completely hollowed out.

[Connecteur]

The most life-threatening accessory I owned was the genuine Apple charger cord that came with my iPad.  After a year or two, the outer sheath began to come off, and it began to throw off sparks before it caught fire.  A genuine replacement cord (that was barely long enough to be useful) was over $50.  I went to the gas station next door and bought a new $3 cord that worked perfectly for years.

[ocset]

As you know, The equation (5) of page 13 of this…
https://www.cde.com/resources/catalogs/AEappGUIDE.pdf
..is what governs wet  electrolytic capacitor lifetime...

Lop = Mv × Lb × 2((Tm – Tc)/10[°C])

                     (Equation (5))

Where
Lop is the expected operating life in h,
Mv is a unitless voltage multiplier for voltage derating,
Lb is the expected operating life in h for full rated voltage
and temperature,
Tm is the maximum permitted internal operating temperature
in degC, and
Ta is the actual capacitor internal operating temperature
in degC.

                     
Its not clear in many wet electrolytic capacitor datasheets, when they say “2000hrs at 105degC”. Do they mean “105degC ambient”, or  “105degC case temperature”, or “105degC internal core temperature”?

The other problem with wet  electrolytics is of course related to the potential for the electrolyte to simply leak out. This exerpt from cornell dubilier  shows the problem with short term high temperature transients in wet electrolytics….

However, as a capacitor heats up toward its maximum permitted
core temperature, the rules change. At temperatures above the
maximum core temperature and by 125 oC for most types the
electrolyte can be driven from capacitor element and the ESR
can increase as much as 10 times. By this mechanism, transient
over-temperature or over-current can permanently increase the
ESR and make the capacitor unusable.

         
           
….so this is the problem, can we be sure that our customer won’t ever temporarily operate the product in such a hot ambient that this temporary overheating of the Electrolytic capacitor occurs?
Another point, is, in Equation (5) above…all those temperature parameters depend on knowing what is the internal ambient temperature in the power supply enclosure. Do we really know where the customer is going to use it, and how hot it may become (even for only short intervals).

In any case, the internal ambient temperature  in a 60W , “fully enclosed plastic case” offline power supply can easily get above 100degC when the external ambient is just 30degC.
Then there’s the storage history of the electrolytic capacitor… before being sold, it may have already been stored for years in a hot warehouse, but they pretend they are new capacitors, and fiddle the date code, if there is even a date code.

[dmills]

You write operating and storage conditions into your spec sheet that you give to the customer, if they choose to play outside your ratings, that's on them, you get to point and laugh.

If you spec that your supply can run without derating in say 40 degrees ambient and supply it in a totally sealed plastic box, then it is on you to design the thing so that it does not overheat... Why is this a mystery?
I have a list of power vendors that I will never again use for getting this wrong.

Storage history you solve by not using the grey market for elcos, FFS. Panasonic/CDW/Chemicon do not in my experience play games like that, and all would be simply fascinated to hear about our CM getting a box of out of date caps from an authorised distribution channel. The rep would I think be beyond narked.

Seriously this stuff is basic to running a professional outfit.

[ocset]

Thanks, ...I mean, if you search digikey for  “Aluminium electrolytic capacitor, 450v, 47uF”…..there are virtually none above 105degc.
If one operates an  El cap above quoted temp, then it can suffer  serious damage, significantly affecting its lifetime. I have a Cornell Dubilier doc which states this. The “10 dgec” law doesn’t work when you go above the quoted temp.
A 60w offline SMPS, totally enclosed in a plastic enclosure, will easily get above 105degC  (internal ambient) at 30degc  external ambient.

Here is such a power supply....one of many out there..
https://www.mouser.co.uk/datasheet/2/260/LPC-60-spec-1109552.pdf

This is why an alternative to El caps is well needed.